Method and arrangement in connection with optical fiber coating

ABSTRACT

The invention relates to a method and an arrangement in connection with coating of an optical fibre, in which a first fibre ( 3   a ) is directed from a fibre pay-off forward in the process via a press head ( 2   a ) forming the coating, and when the first fibre ( 3   a ) ends, a new fibre ( 3   b ) is directed to the press head ( 2   a ) in advance, and when the first fibre ( 3   a ) ends, a roll device ( 7 ) grips both the first fibre and the new fibre so that both fibres ( 3   a   , 3   b ) are caught between freely rotating rolls ( 7   a   , 7   b ) of the roll device ( 7 ), whereupon the tail of the first fibre ( 3   a ) makes the rolls ( 7   a   , 7   b ) of the roll device rotate, and the rotational movement of the rolls pushes the new fibre ( 3   b ) to the press head ( 2   a ) at a speed equal to that of the line.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method in connection with coating of anoptical fibre or the like, wherein a first fibre or the like is directedfrom a fibre pay-off forward in the process via a press head forming thecoating, and when the first fibre or the like ends, a new fibre or thelike is guided to the press head and through it. The invention alsorelates to an arrangement in connection with an optical fibre or thelike.

2. Description of Related Art

When a fibre ends in an optical fibre coating process, such as a tightbuffer process, also the buffer supplied from the press head breaks inprior art solutions. In such a situation, the line operator has beenforced to manually thread the buffer again through the line, in otherwords to restart the process. In such a restart the amount of wastedfibre rapidly increases to several dozens of meters, which also raisesthe costs due to the loss of material. Another problem has been thatmanual threading is laborious and slow, which further increases thecosts and reduces the degree of use of the line. Further, manualthreading is also an obvious security risk.

SUMMARY OF THE INVENTION

The purpose of the invention is to provide a method and an arrangementwhich eliminate the prior art drawbacks. This is achieved with themethod and arrangement according to the invention. The method accordingto the invention is characterized in that the new fibre or the like isdirected to the vicinity of the press head in advance, so that when thefirst fibre or the like ends, a roll device grips both the first fibreand the new fibre or the like so that both fibres or the like are caughtbetween freely rotating rolls of the roll device, whereupon the tail ofthe first fibre or the like makes the rolls of the roll device rotate,whereafter the rotational movement of the rolls pushes the new fibre orthe like to the press head at a speed equal to that of the line. Thearrangement according to the invention is, in turn, characterized inthat the arrangement comprises a holder and a roll device comprising twofreely rotating rolls, which have two positions: a first position wherethe rolls are spaced apart and a second position where the rolls arepressed together, the rolls being arranged before the press head atopposite sides of the fibre line passing through the press head, and theholder being arranged to keep the end of the new fibre or the like nearthe press head such that the end of the new fibre or the like ispositioned between the rolls placed in the first position of the rolldevice as the first fibre or the like travels from between the rolls ofthe roll device to the press head, and that when the first fibre or thelike ends, the rolls of the roll device are arranged to move into thesecond position so that both the first fibre and the new fibre or thelike remain between the rolls and the tail of the first fibre or thelike makes the rolls rotate, and the holder is arranged to open,whereupon the rotational movement of the rolls pushes the new fibre orthe like to the press head at a speed equal to that of the line.

A primary advantage of the invention is that it avoids thetime-consuming and laborious manual restart, wherefore the amount ofwasted fibre remains as small a possible. The invention thus provideseconomic advantages due to lower fibre costs and an improved degree ofuse of the line. Further, the structure of the arrangement according tothe invention is simple and reliable. The invention also improves theoperational safety of the line since the operator does not have tothread a fibre manually through the entire line or to feed a new fibreinto the process during the operation of the line.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be described in greater detail bymeans of a preferred embodiment shown in the accompanying drawing, inwhich

FIG. 1 is a general view of a fibre coating line,

FIG. 2 is a side view of an arrangement according to the invention, and

FIG. 3 shows the arrangement of FIG. 2 viewed from the direction oftravel of the fibre.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows generally a line used for coating an optical fibre. In FIG.1, reference numeral 1 generally denotes fibre pay-offs and referencenumeral 2 denotes a press apparatus comprising an actual press head andother means which are used to provide the surface of an optical fibrewith a coating. The optical fibre is denoted in FIG. 1 by referencenumeral 3. Reference numeral 4 denotes generally means used for coolingthe coated fibre, and reference numeral 5 correspondingly denotes meansfor winding the coated fibre onto a reel. Reference numeral 10 denotesan arrangement according to the invention, reference numeral 11 denotesa diameter measuring device, and reference numeral 12 denotes a pullingdevice for an optical fibre cable. Reference numeral 13 denotes a linecontrol unit.

The aforementioned matters constitute fully conventional technology tothose skilled in the art, wherefore they will not be described ingreater detail herein.

When a fibre is coated on a line shown in FIG. 1, in prior art solutionsthe coating process has been interrupted after the fibre supplied fromthe fibre pay-off 1 has ended, where after the operator has been forcedto manually thread a new fibre from the fibre pay-off through the entireline. However, this kind of procedure causes problems, as describedabove.

The invention relates to a method and an arrangement which enablecontinuous fibre coating. Therefore the line operator is able to preparea new fibre during the process to be ready when the old fibre runs out.When this happens, the arrangement according to the invention begins tooperate and feeds a new fibre to the press head without the processbeing interrupted. The fibre joint can be marked and removed insubsequent process steps.

The arrangement according to the invention is described in FIGS. 2 and3. The arrangement shown in FIGS. 2 and 3 is placed on the coating lineat a point immediately preceding the press head. The arrangementcomprises a holder 6 and a roll device 7, which comprises two freelyrotating rolls 7 a, 7 b. The rolls 7 a, 7 b are made movable with twopositions: a first position where the rolls are spaced apart and asecond position where the rolls are pressed together. FIGS. 2 and 3 showthe first position of the rolls. The rolls 7 a, 7 b are arranged beforethe press head 2 a at opposite sides of the fibre line passing throughthe press head.

The holder 6 is arranged to keep the end of a new fibre or the like nearthe press head, such that the end of the new fibre or the like 3 b ispositioned between the rolls 7 a, 7 b placed in the first position ofthe roll device as the first fibre or the like 3 a travels between therolls of the roll device to the press head. This is shown clearly inFIG. 2.

When the first fibre or the like 3 a ends, the rolls 7 a, 7 b of theroll device are arranged to move to the second position, so that boththe first fibre and the new fibre or the like remain between the rolls,and the tail of the first fibre or the like makes the rolls 7 a, 7 brotate. In this situation, the holder 6 is arranged to open so that therotating movement of the rolls 7 a, 7 b pushes the new fibre or the like3 b to the press head 2 a at a speed equal to that of the line.

The rolls 7 a, 7 b are moved together or spaced apart by means ofpressurized air, for example. The rotation of the rolls does not requireseparate actuators, but the rolls rotate freely. The rotational movementof the rolls is achieved solely by means of the tail of the first fibreor the like.

As stated above, the rolls 7 a, 7 b are open, which means that they arespaced apart during the coating process and the first fibre or the like3 a travels from between them to the press head 2 a. The operator mayplace a new fibre in the holder 6 already during the process so that theend of the new fibre extends from between the rolls to a guide cone 2 bprovided in the press head 2 a. This situation is shown in FIG. 2.

When the first fibre or the like 3 a ends, the control system of theapparatus is informed of the situation, whereafter the rolls 7 a, 7 bare pressed together and the holder 6 is opened. Control information canbe received from any suitable component, such as a fibre break sensorprovided in the fibre pay-off. When the rolls press against one another,both the tail of the first fibre or the like 3 a and the beginning ofthe new fibre remain between the rolls, and the progressive movement ofthe tail of the first fibre 3 a makes the rolls 7 a, 7 b rotate,whereupon the rotational movement of the rolls moves or pushes the newfibre or the like 3 b towards the press head at a speed equal to that ofthe line. Since the coating emerging from the press head breaks easilydue to variation in tension, the line control unit may adjust the lineprocess parameters momentarily during the jointing process so that thetension variation is minimized. For example, the line control may supplyan additional accelerating signal to the fibre pay-off in order toprovide sufficiently fast acceleration during the jointing processcompared to normal operation.

The holder 6 can be formed of, for example, two flat surfaces 6 a, 6 bthat are arranged to press together and to move to a distance from oneanother in a desired manner. The holder can also be implemented by meansof two rolls, which are arranged such that they can be pressed togetherand spaced apart. The rolls must be mounted in bearings so that theyonly rotate in the direction of travel of the fibre or the line.

The operation of both the holder and the roll device can be implementedby means of any suitable arrangement, such as the use of pressurizedair, an electric motor and so forth.

The embodiment described above is not intended to restrict the inventionin any way, but the invention can be varied freely within the scope ofthe claims. Therefore it is clear that the arrangement according to theinvention or the details thereof do not have to be exactly identical tothose shown in the figures, but also other solutions are possible. Forexample, the invention is not restricted to only one fibre, but theinvention can also be applied in the coating of more than one fibre. Theexpression ‘fibre or the like’ must be understood in the aforementionedscope. Nor is the invention restricted to only one coating material, butit can be applied in connection with various materials, in which casethe invention is modified according to the needs of the material.Examples include PVC and polyamide. When using polyamide, the fibre mustfirst be dried with a heat radiator, for example, which can be placedbefore the holder. Such an arrangement is naturally included within thescope of the invention. It is also clear that the scope of the inventionincludes an application comprising air blow that hardens the plasticafter the press head, so that the coating does not break during thejointing step. The invention can also be applied in connection with abreaking device, wherein the reel storing the first fibre is not emptiedentirely, but the fibre is cut at a certain moment and the process iscontinued with a new fibre as described above. Further, it is clear thatthe scope of the invention also includes an application where thejointing is activated already before the first fibre or the like breaksor is cut.

What is claimed is:
 1. A method in connection with coating of an opticalfibre in a fibre coating line, wherein a first fibre (3 a) is directedfrom a fibre pay-off forward in the process via a press head (2 a)forming the coating, and when the first fibre (3 a) ends, a new fibre (3b) is guided to the press head (2 a) and through it, characterized inthat the new fibre (3 b) is directed to the press head (2 a) in advance,so that when the first fibre (3 a) ends, a roll device (7) grips boththe first fibre and the new fibre so that both fibres (3 a, 3 b) arecaught between freely rotating rolls (7 a, 7 b) of the roll device (7),whereupon the tail of the first fibre (3 a) makes the rolls (7 a, 7 b)of the roll device rotate, whereafter the rotational movement of therolls pushes the new fibre in a fibre coating line (3 b) to the presshead (2 a) at a speed equal to that of the line.
 2. An arrangement inconnection with coating of an optical fibre in a fibre coating line,wherein a first fibre (3 a) is arranged to be directed from a fibrepay-off forward in the process via a press head (2 a) forming thecoating, and when the first fibre (3 a) ends, a new fibre (3 b) isarranged to be guided to the press head (2 a) and through it,characterized in that the arrangement comprises a holder (6) and a rolldevice (7) comprising two freely rotating rolls (7 a, 7 b), which havetwo positions: a first position where the rolls (7 a, 7 b) are spacedapart and a second position where the rolls (7 a, 7 b) are pressedtogether, the rolls being arranged before the press head at oppositesides of the fibre line passing through the press head (2 a), and theholder (6) being arranged to keep the end of the new fibre (3 b)positioned between the rolls (7 a, 7 b) placed in the first position ofthe roll device as the first fibre (3 a) travels from between the rollsof the roll device to the press head, and that when the first fibre (3a) ends, the rolls (7 a, 7 b) of the roll device are arranged to moveinto the second position so that both the first fibre and the new fibreremain between the rolls and the tail of the first fibre (3 a) makes therolls (7 a, 7 b) rotate, and the holder (6) is arranged to open,whereupon the rotational movement of the rolls (7 a, 7 b) pushes the newfibre (3 b) to the press head (2 a) at a speed equal to that of theline.
 3. An arrangement according to claim 2, characterized in that theholder (6) is formed of two surfaces (6 a, 6 b), which are arranged topress together.
 4. An arrangement according to claim 3, characterized inthat the operation of both the holder (6) and the roll device (7) isimplemented by pressurized air.
 5. An arrangement according to claim 3,characterized in that the operation of both the holder (6) and the rolldevice (7) is implemented by an electric motor.
 6. An arrangementaccording to claim 2, characterized in that the holder (6) is formed bymeans of two rolls which are arranged to press together and to rotateonly in the direction of travel of the fibre.
 7. An arrangementaccording to claim 6, characterized in that the operation of both theholder (6) and the roll device (7) is implemented by pressurized air. 8.An arrangement according to claim 6, characterized in that the operationof both the holder (6) and the roll device (7) is implemented by anelectric motor.
 9. An arrangement according to claim 2, characterized inthat the operation of both the holder (6) and the roll device (7) isimplemented by pressurized air.
 10. An arrangement according to claim 2,characterized in that the holder (6) and the roll device (7) isimplemented by an electric motor.